1. Field of the Invention
The present invention relates to movable body apparatuses, movable body drive methods, exposure apparatuses, exposure methods, and device manufacturing methods, and more particularly, to a movable body apparatus including a moving body which is movable along a predetermined plane and a movable body drive method to drive the movable body, an exposure apparatus which is equipped with the movable body apparatus and an exposure method which uses the movable body drive method, and a device manufacturing method which uses the exposure apparatus or the exposure method.
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing electron devices (microdevices) such as semiconductor devices (such as integrated circuits) and liquid crystal display devices, exposure apparatuses such as a projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner)) are mainly used.
In these types of exposure apparatuses, the position of a fine movement stage which moves two-dimensionally, holding a substrate (hereinafter generally referred to as a wafer) such as a wafer or a glass plate on which a pattern is transferred and formed, was measured using a laser interferometer in general. However, requirements for a fine movement stage position control with higher precision are increasing due to finer patterns that accompany higher integration of semiconductor devices recently, and as a consequence, short-term variation of measurement values due to the influence of temperature fluctuation and/or temperature gradient of the atmosphere on the beam path of the laser interferometer can no longer be ignored.
To improve such an inconvenience, various inventions related to an exposure apparatus that has employed an encoder having a measurement resolution, of the same level or better than a laser interferometer as the position measuring device of the fine movement stage have been proposed (refer to, e.g., PCT International Publication No. 2007/097379). However, in the liquid immersion exposure apparatus disclosed in PCT International Publication No. 2007/097379 (the corresponding U.S. Patent Application Publication No. 2008/0088843), there still were points that should have been improved, such as a threat of the wafer stage (a grating installed on the wafer stage upper surface) being deformed when influenced by heat of vaporization and the like when the liquid evaporates.
To improve such an inconvenience, for example, in PCT International Publication No. 2008/038752 (the corresponding U.S. Patent Application Publication No. 2008/0094594), as a fifth embodiment, an exposure apparatus is disclosed which is equipped with an encoder system that has a grating arranged on the upper surface of a wafer stage configured by a light transmitting member and measures the displacement of the wafer stage related to the periodic direction of the grating by making a measurement beam from an encoder main body placed below the wafer stage enter the wafer stage and be irradiated on the grating, and by receiving a diffraction light which occurs in the grating. In this apparatus, because the grating is covered with a cover glass, the grating is immune to the heat of vaporization, which makes it possible to measure the position of the wafer stage with high precision.
However, in the exposure apparatus related to the fifth embodiment of PCT International Publication No. 2008/038752, because the encoder main body is provided at the stage surface plate supported by suspension by the projection optical system surface plate via the suspension support member, vibration during exposure of the exposure apparatus could travel to the stage surface plate via the projection optical system surface plate and the suspension support member, which could incline the optical axis of the encoder head, and cause the measurement accuracy of the encoder system to decline.